The Culture of Healthcare Evidence-Based Practice Lecture c This material (Comp2_Unit5c) was...

The Culture of Healthcare

Evidence-Based Practice

Lecture c

This material (Comp2_Unit5c) was developed by Oregon Health and Science University, funded by the Department of Health and Human Services, Office of the National Coordinator for Health Information

Technology under Award Number IU24OC000015.

Evidence-Based PracticeLearning Objectives

• Define the key tenets of evidence-based medicine (EBM) and its role in the culture of health care (Lectures a, b)

• Construct answerable clinical questions and critically appraise evidence answering them (Lecture b)

• Apply EBM for intervention studies, including the phrasing of answerable questions, finding evidence to answer them, and applying them to given clinical situations (Lecture c)

• Understand EBM applied to the other key clinical questions of diagnosis, harm, and prognosis (Lectures d, e)

• Discuss the benefits and limitations to summarizing evidence (Lecture f)

• Describe how to implement EBM in clinical settings through clinical practice guidelines and decision analysis (Lecture g)

2Health IT Workforce Curriculum Version 3.0/Spring 2012

The Culture of Healthcare Evidence-Based Practice

Lecture c

Using EBM To Assess Questions About Interventions

• Questions concerning benefit of a clinical intervention to treat or prevent disease

• Can include drug therapy, diet therapy, surgery, alternative medicine, etc.

• Best evidence comes from a randomized controlled trial (RCT) or meta-analysis of RCTs– Patients similar in all regards with

exception of intervention applied



Lecture c

Why Are RCTs The Best Evidence For Interventions?

• Reduction in bias– Vitamin C to prevent the common cold (Douglas,

Chalker, & Treacy, 2000)– Women’s Health Initiative (Anonymous, 2002)

• Emphasis on clinical end-points and patient-oriented outcomes– Cardiac Arrhythmia Suppression Trial (Epstein, et al.,

1993)

• “New” treatments are not necessarily better– In radiation oncology, trials of new treatments are as

likely as not to be successful (Soares, et al., 2005)4

Health IT Workforce Curriculum Version 3.0/Spring 2012


Lecture c

Other Issues For RCTs

• Quality of study inversely related to magnitude of treatment effect (Moher, et al., 1998)

• Lower-quality (e.g., non-RCT) studies more likely to be later “overturned” (Ioannidis, 2005)

• But well-designed observational studies may be just as good (Benson & Hartz, 2000)



Lecture c

History Of RCTs

• James Lind, British naval doctor and surgeon (1717-1794) demonstrated that lemons and oranges improved health of sailors with scurvy over those who did not receive them (Lindemann, 1999)

• First true RCT performed in UK in 1940s, demonstrating superiority of streptomycin over placebo for tuberculosis (Anonymous, 1948)



Lecture c

How Do We Critically Appraise An Intervention Study?

• Remember the questions to be asked of any study

– Are the results valid?

– What are the results?

– Can the results be applied to patient care?



Lecture c

Questions To Ask About A Study On Intervention

• Are the results valid?– Did experimental and control groups begin the

study with a similar prognosis?• Were patients randomized?• Was randomization concealed (blinded or

masked)?• Were patients analyzed in the groups to which they

were randomized?• Were patients in treatment and control groups

similar with respect to known prognosis?



Lecture c

A Study On An Intervention (continued)

• Are the results valid? (continued)

– Did experimental and control groups retain a similar prognosis after the study started?• Were patients aware of group allocation?• Were clinicians aware of group allocation?• Were assessors aware of group allocation?• Was follow-up complete?



Lecture c

A Study On An Intervention (continued)

• What are the results?– How large was the treatment effect?

• What was the relative risk reduction?• What was the absolute risk reduction?

– How precise was the estimate of treatment effect?• Were the confidence intervals or p-values stated?

• Can the results be applied to patient care?– Were the study patients similar to my patient?– Were all clinically important outcomes considered?– Are the likely treatment benefits worth the potential

harm and costs?



Lecture c

Examples Of RCTs• Women’s Health Initiative (WHI)

– Previous non-RCT studies suggested women who used postmenopausal hormone replacement therapy (HRT) at any time had lower mortality overall and from heart disease

• In general, RCTs and observational studies had yielded conflicting results

– WHI study was RCT that “settled the issue” (Anonymous, 2002; Lowe, 2002), showing no benefit and possible harm from increased risk of breast cancer and cardiovascular disease

• Observational studies found to be confounded by non-similarities between users and non-users (Humphrey, Chan, & Sox, 2002)



Lecture c

Examples of RCTs (continued)

• Eradication of H. pylori to prevent recurrence of gastric cancer (Fukase, et al., 2008)

• H. pylori is bacteria associated with peptic ulcer disease

• When eradicated with antibiotics in patients with cancer of stomach, recurrence of cancer is less likely to occur

– Relative risk reduction = 66%12

Health IT Workforce Curriculum Version 3.0/Spring 2012


Lecture c

Evidence-Based PracticeSummary – Lecture c



Lecture c

• Most common type of question in EBM is about intervention, sometimes called treatment or therapy

• Best evidence for intervention is the RCT, or a systematic review of multiple RCTs on a given topic

Evidence-Based PracticeReferences – Lecture c



Lecture c

References

Anonymous. (1948). Streptomycin treatment of pulmonary tuberculosis. British Medical Journal, 30, 769-782.

Anonymous. (2002). Risks and benefits of estrogen plus progestin in healthy postmenopausal women - principal results from the Women's Health Initiative randomized controlled trial. Journal of the American Medical Association, 288, 321-333.

Benson, K., & Hartz, A. (2000). A comparison of observational studies and randomized, controlled trials. New England Journal of Medicine, 342, 1878-1886.

Douglas, R., Chalker, E., & Treacy, B. (2000). Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews, 2, CD000980.

Epstein, A., Hallstrom, A., Rogers, W., Liebson, P., Seals, A., Anderson, J., . . . Wyse, D. (1993). Mortality following ventricular arrhythmia suppression by encainide, flecainide, and moricizine after myocardial infarction. The original design concept of the Cardiac Arrhythmia Suppression Trial (CAST). Journal of the American Medical Association, 270, 2451-2455.

Fukase, K., Kato, M., Kikuchi, S., Inoue, K., Uemura, N., Okamoto, S., . . . Asaka, M. (2008). Effect of eradication of Helicobacter pylori on incidence of metachronous gastric carcinoma after endoscopic resection of early gastric cancer: an open-label, randomised controlled trial. Lancet, 372, 392-397.

Humphrey, L., Chan, B., & Sox, H. (2002). Postmenopausal hormone replacement therapy and the primary prevention of cardiovascular disease. Annals of Internal Medicine, 137, 273-284.

Ioannidis, J. (2005). Contradicted and initially stronger effects in highly cited clinical research. Journal of the American Medical Association, 294, 218-228.

Lindemann, M. (1999). Medicine and Society in Early Modern Europe. Cambridge, England: Cambridge University Press.

Evidence-Based PracticeReferences – Lecture c (continued)

Lowe, J. (2002). Estrogen plus progestin increased coronary heart disease and breast cancer events in postmenopausal women. ACP Journal Club, 137, 41.

Moher, D., Pham, B., Jones, A., Cook, D., Jadad, A., Moher, M., . . . Klassen, T. (1998). Does quality of reports of randomised trials affect estimates of intervention efficacy reported in meta-analyses? Lancet, 352, 609-613.

Soares, H., Kumar, A., Daniels, S., Swann, S., Cantor, A., Hozo, I., . . . Djulbegovic, B. (2005). Evaluation of new treatments in radiation oncology: are they better than standard treatments? Journal of the American Medical Association, 293, 970-978.



Lecture c

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